Combination of gefitinib and olaparib versus gefitinib alone in EGFR mutant non-small-cell lung cancer (NSCLC): A multicenter, randomized phase II study (GOAL)

OBJECTIVES

Progression-free survival (PFS) and response rate to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) varies in patients with non-small-cell lung cancer (NSCLC) driven byEGFR mutations, suggesting that other genetic alterations may influence oncogene addiction. Low BRCA1 mRNA levels correlate with longer PFS in erlotinib-treated EGFR-mutant NSCLC patients. Since the poly (ADP-ribose) polymerase (PARP) inhibitor, olaparib, may attenuate and/or prevent BRCA1 expression, the addition of olaparib to gefitinib could improve outcome in EGFR-mutant advanced NSCLC.

MATERIALS AND METHODS

GOAL was a multicenter, randomized phase IB/II study performed in two countries, Spain and Mexico. Eligible patients were 18 years or older, treatment-naïve, pathologically confirmed stage IV NSCLC, with centrally confirmed EGFR mutations and measurable disease. Patients were randomly allocated (1:1) to receive gefitinib 250 mg daily or gefitinib 250 mg daily plus olaparib 200 mg three times daily in 28-day cycles. The primary endpoint was PFS. Secondary endpoints included overall survival (OS), response rate, safety and tolerability.

RESULTS

Between September 2013, and July 2016, 182 patients underwent randomization, 91 received gefitinib and 91 received gefitinib plus olaparib. There were no differences in gender, age, smoking status, performance status, presence of bone and brain metastases or type ofEGFR mutation. Median PFS was 10.9 months (95 % CI 9.3-13.3) in the gefitinib arm and 12.8 months (95 % CI 9.1-14.7) in the gefitinib plus olaparib arm (HR 1.38, 95 % CI 1.00-1.92; p = 0.124). The most common adverse events were anemia, 78 % in gefitinib plus olaparib group, 38 % in gefitinib arm, diarrhea, 65 % and 60 %, and fatigue, 40 % and 32 %, respectively.

CONCLUSIONS

The gefitinib plus olaparib combination did not provide significant benefit over gefitinib alone. The combination's safety profile showed an increase in hematological and gastrointestinal toxicity, compared to gefitinib alone, however, no relevant adverse events were noted.

Targeting DNA Repair in Cancer: Beyond PARP Inhibitors

Germline aberrations in critical DNA-repair and DNA damage-response (DDR) genes cause cancer predisposition, whereas various tumors harbor somatic mutations causing defective DDR/DNA repair. The concept of synthetic lethality can be exploited in such malignancies, as exemplified by approval of poly(ADP-ribose) polymerase inhibitors for treating BRCA1/2-mutated ovarian cancers. Herein, we detail how cellular DDR processes engage various proteins that sense DNA damage, initiate signaling pathways to promote cell-cycle checkpoint activation, trigger apoptosis, and coordinate DNA repair. We focus on novel therapeutic strategies targeting promising DDR targets and discuss challenges of patient selection and the development of rational drug combinations.

SIGNIFICANCE

Various inhibitors of DDR components are in preclinical and clinical development. A thorough understanding of DDR pathway complexities must now be combined with strategies and lessons learned from the successful registration of PARP inhibitors in order to fully exploit the potential of DDR inhibitors and to ensure their long-term clinical success. Cancer Discov; 7(1); 20-37. ©2016 AACR.

An Update on Poly(ADP-ribose)polymerase-1 (PARP-1) Inhibitors: Opportunities and Challenges in Cancer Therapy

Poly(ADP-ribose)polymerase-1 (PARP-1) is a critical DNA repair enzyme in the base excision repair pathway. Inhibitors of this enzyme comprise a new type of anticancer drug that selectively kills cancer cells by targeting homologous recombination repair defects. Since 2010, important advances have been achieved in PARP-1 inhibitors. Specifically, the approval of olaparib in 2014 for the treatment of ovarian cancer with BRCA mutations validated PARP-1 as an anticancer target and established its clinical importance in cancer therapy. Here, we provide an update on PARP-1 inhibitors, focusing on breakthroughs in their clinical applications and investigations into relevant mechanisms of action, biomarkers, and drug resistance. We also provide an update on the design strategies and the structural types of PARP-1 inhibitors. Opportunities and challenges in PARP-1 inhibitors for cancer therapy will be discussed based on the above advances.